New Computer Help

[Husar]

Well, I'm not an expert about power supplies but afaik most of them are best between around 50 to 80% of their output or something, then you have different efficiency curves, meaning they may be more efficient at 60% or whatever. I'm sure Xiahou, Whacker, Caravel could say more about it than I can.
Going for one that has 1000Watts when you just want an office PC is certainly a good way to waste money though.

My old 420W PSU was apparently enough for a Core3Duo E6600 and a 7950GT, but like I said, going for one from a good brand might be a good idea, too bad that I don'rt really know which brands are actually good.